Sets and Colours

I want to visualize connections between atoms, and each (half-)line must be
coloured by atom's colour. I have something like this:

N -> (set(X, Y, Z), (Red, Green, Blue)) ,

N is in Integer1DSet(Max),
set(X, Y ,Z):= Gridded3DSet(X, Y, Z) with mainfold dimension 1 (lines),
ScalarMaps are XAxis, YAxis, ZAxis, Red, Green, Blue.

So, if all colour elements are the same (Red1=...=RedMax,
Green1=...=GreenMax, Blue1=...=BlueMax) I see only grey lines instead of my
own colour. Is it right? Where can I read how it works?