diff --git a/.travis.yml b/.travis.yml
index 37144abc..6b472238 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,6 +19,7 @@ matrix:
 addons:
   apt:
     packages:
+      - libqt5gui5  # pyqt5>5.11 otherwise cannot load the xcb platform plugin
       - libflann-dev
 
 install:
diff --git a/pygsp/plotting.py b/pygsp/plotting.py
index eb152c96..56fcc6bf 100644
--- a/pygsp/plotting.py
+++ b/pygsp/plotting.py
@@ -299,6 +299,8 @@ def _plot_graph(G, vertex_color, vertex_size, highlight,
         Signal to plot as vertex color (length is the number of vertices).
         If None, vertex color is set to `graph.plotting['vertex_color']`.
         Alternatively, a color can be set in any format accepted by matplotlib.
+        Each vertex color can by specified by an RGB(A) array of dimension
+        `n_vertices` x 3 (or 4).
     vertex_size : array-like or int
         Signal to plot as vertex size (length is the number of vertices).
         Vertex size ranges from 0.5 to 2 times `graph.plotting['vertex_size']`.
@@ -319,6 +321,8 @@ def _plot_graph(G, vertex_color, vertex_size, highlight,
         ranges from 0.2 to 0.9.
         If None, edge color is set to `graph.plotting['edge_color']`.
         Alternatively, a color can be set in any format accepted by matplotlib.
+        Each edge color can by specified by an RGB(A) array of dimension
+        `n_edges` x 3 (or 4).
         Only available with the matplotlib backend.
     edge_width : array-like or int
         Signal to plot as edge width (length is the number of edges).
@@ -405,20 +409,26 @@ def normalize(x):
             return np.full(x.shape, 0.5)
         return 0.75 * (x - x.min()) / ptp + 0.25
 
-    def is_single_color(color):
+    def is_color(color):
+
         if backend == 'matplotlib':
             mpl, _, _ = _import_plt()
-            return mpl.colors.is_color_like(color)
-        elif backend == 'pyqtgraph':
-            # No support (yet) for single color with pyqtgraph.
-            return False
+            if mpl.colors.is_color_like(color):
+                return True  # single color
+            try:
+                return all(map(mpl.colors.is_color_like, color))  # color list
+            except TypeError:
+                return False  # e.g., color is an int
+
+        else:
+            return False  # No support for pyqtgraph (yet).
 
     if vertex_color is None:
         limits = [0, 0]
         colorbar = False
         if backend == 'matplotlib':
             vertex_color = (G.plotting['vertex_color'],)
-    elif is_single_color(vertex_color):
+    elif is_color(vertex_color):
         limits = [0, 0]
         colorbar = False
     else:
@@ -438,8 +448,8 @@ def is_single_color(color):
 
     if edge_color is None:
         edge_color = (G.plotting['edge_color'],)
-    elif not is_single_color(edge_color):
-        edge_color = np.array(edge_color).squeeze()
+    elif not is_color(edge_color):
+        edge_color = np.asarray(edge_color).squeeze()
         check_shape(edge_color, 'Edge color', G.n_edges)
         edge_color = 0.9 * normalize(edge_color)
         edge_color = [
diff --git a/pygsp/tests/test_plotting.py b/pygsp/tests/test_plotting.py
index 28f0aa95..0aa29d44 100644
--- a/pygsp/tests/test_plotting.py
+++ b/pygsp/tests/test_plotting.py
@@ -116,11 +116,14 @@ def test_signals(self):
         G.plot()
         def test_color(param, length):
             for value in ['r', 4*(.5,), length*(2,), np.ones([1, length]),
-                          np.random.RandomState(42).uniform(size=length)]:
+                          np.random.RandomState(42).uniform(size=length),
+                          np.ones([length, 3]), ["red"] * length,
+                          np.random.RandomState(42).rand(length, 4)]:
                 params = {param: value}
                 G.plot(**params)
             for value in [10, (0.5, 0.5), np.ones([length, 2]),
-                          np.ones([2, length, 3])]:
+                          np.ones([2, length, 3]),
+                          np.ones([length, 3]) * 1.1]:
                 params = {param: value}
                 self.assertRaises(ValueError, G.plot, **params)
             for value in ['r', 4*(.5)]: