Scott,
Quote
Section #1: NEC® Specified Color Codes for Conductors: ...

* UNGROUNDED CONDUCTOR(s):

--60 VAC to 600 VAC--

Black, Red, Blue, Brown, Orange, Yellow, Pink, Purple (Violet).
This seems to imply that you are required to use specific colors, but that is not in the code.
Don

Don(resqcapt19)