Text Color configurations are stored in the DSDATC lump. These defaults can be changed by replacing the lump.
Each line of the DSDATC lump has a text component and a color index:
text_component color_index
Various elements of the extended hud, the automap, and the menus can be changed. The color indices correspond to entries in the DSDACR lump.
You can find the current default configuration here.