When using AutoCAD, I have always used color to differentiate parts, especially in complex assemblies. It helps the user distinguish the various systems. If there is a complex mechanism, I use color to help the user of the drawings to see what moves as a group.
It has been a number of years since I used SW regularly, and I recall that the approach to color in drawings was difficult enough that I just abandoned the idea. I have been hoping that there have been improvements in this area.
Specifically, I would like to choose a view rendering style that has lines that are the color of the object, and no shading. Or alternatively (though I doubt this is possible), the objects are colored in, but not shaded. Ideally, the color of the objects is somewhat faded. When they are not simply filled in with the objects color, but are shaded based on some light source, many of the faces end up too dark.