Cooper was a Marine, as almost all of us know. His concept of color codes is not so different from the separate but related concepts of "Threat Level" and "Weapons Status."
Threat Level is based on regional intelligence assessments, while Weapons Status is based on ROE and perceived readiness requirement - which is influenced by, but not the same as, Threat Level.
The higher the Weapons Status, the faster the theoretical response capability to threat, but the higher the potential for ND / AD and fratricide. (Particularly with automated systems.)
Cooper basically amalgamated the concepts, and codified for individual vs unit use.