Most autos have the color code listed on the same tag as the VIN. This tag is typically on the driver’s side door jamb. If it's not visible there, check the passenger side. Some manufacturers will place the tag in the trunk of the vehicle (Audi/VW) or the glovebox (GM).
Pictured below are some examples of common manufacturer tags:
GM (General Motors)/Cadillac/Pontiac/GMC