The colors you choose are up to you, the NEC would allow purple, pink and brown for 480 volt.
However in some instances the NEC does require that the colors you choose to be listed at the panel.
In the 2002 NEC it applied only to multiwire branch circuits.
210.4 Multiwire Branch Circuits.(D) Identification of Ungrounded Conductors. Where more than one nominal voltage system exists in a building, each ungrounded conductor of a multiwire branch circuit, where accessible, shall be identified by phase and system. This means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means and shall be permanently posted at each branch-circuit panelboard.
Now in the 2005 it applies to all circuits in some buildings.
Look at 2005 - 210.5(C)
