Communication covers the dissemination of information using colours, involving systems ranging from the simple signal to the linguistic and semiotic. It ranges from popular flag-waving to colour in Information Technology and Artificial Intelligence, and from Graphics in advertising to Synaesthesia.

The Semiotics of Colour
For a colour symbolic system to work like a language there are three basic requirements:

1 PRAGMATICS There needs to be a limited field of application and defined scope.
2 SEMANTICS There have to be communicating units, like words in language.
3 SYNTACTICS There needs to be some kind of grammatical syntax to bring out the meaning of the communication.

References
See MORRIS, C. (1941) Signs, Language and Behaviour. NY. (The classic work on symbolic systems)
PAVEY, D. (1990) The Little Green Man . Micro Academy (A video about colour in road signs as a symbolic system)