cl-colors
cl-colors contains named RGB colors like +blue+ and +darkolivegreen+. Calling it a graphics library is a bit of an overstatement, but its primary purpose is to be used in graphics. It supports alpha channels and HSV conversion/manipulation. The license is LLGPL.

You can obtain the library from Github or install using ASDF-install.

ASDF-install package (obsolete) http://github.com/tpapp/cl-colors/tarball/master