Is there any way to color wires in node editor? If not, are there any add-ons for coloring wires based on the body color of the output node? It seems like it should be pretty simple to do and I've downloaded textures with colored wires but I have no idea how it was done.
If you are trying to achieve an effect similar to the one you get with the Blender internal renderer, you can use the
Wireframe node to separate edges from the rest:
The white (1) regions are at the specified distance from the edges, and the black (0) regions are not. You can pass these values to the mix shader to use separate shaders for these two regions: