Three suggestions about cable coloring :
Allow cables to be painted inside inventory, and those when wont immediatly connect to other colored cables.
Allow cables to retain color upon removal. Color can be removed by placing the colored cable in the crafting, like the painter.
A new set of colors, which is made of redstone/glowstone and a dye and (glowing color), those colors will prevent cables from connecting to machines and any other color different from its own.