NaB, as the cookbook says The lamp will light up with the colored signal that is greater than zero and earliest in this list: Red, Green, Blue, Yellow, Pink, Cyan, White.

Green is before yellow, so the lamp lights up green no matter if yellow is present or not.

So the colors list is fixed and ...

version: 0.15.30

Following an inspiration from the Circuit Network Cookbook I have done this setup to provide multiple colors for a single lamp depending on the input value:
2017-07-21_14h10_59.png

When I decrease the input "I" the color changes for blue, green, red and switching the lamp off ...

Version: 0.15.30

There's no output from the Decider Combinator when the field "input count" is chosen.