G.add_edge(3, 4, color='g', weight=6)
pos = nx.circular_layout(G)
edges = G.edges()
colors = [G[u][v]['color'] for u, v in edges]
weights = [G[u][v]['weight'] for u, v in edges]
nx.draw(G, pos, edges=edges, edge_color=colors, width=weights)
networkx - change color/width according to edge attributes - inconsistent result