Many books in computer science are (informally) known by the color of their cover, or by the picture which adorns it. Examples:
Some of the "colored" books are context dependent (including things outside of computer science). For example, the Kelly Blue Book (also commonly known as the Blue Book) is a periodical listing values for various makes and models of used cars. The Orange Book mentioned above is a security manual published by the UnitedStates Department of Defense; the phrase also refers to one of the various standards documents describing the compact disc.
In ExtremeProgramming outfits, the slew of AddisonWesley books in its XpSeries are often referred to by the color of their cover.