 vertex drawer is L{MatplotlibVertexDrawer}.
        @param edge_drawer_factory: a factory method that returns an
            L{AbstractEdgeDrawer} instance bound to a given Matplotlib Axes.
            The factory method must take two parameters: the Axes and the palette
            to be used for drawing colored edges. The default edge drawer is
            L{MatplotlibEdgeDrawer}.
        &#34;&#34;&#34;
        self.ax = ax
        self.vertex_drawer_factory = vertex_drawer_factory
        self.edge_dra