Many books in computer science are (informally) known by the color of their cover, or by the picture which adorns it.  Examples:

* TheDragonBook (''CompilersPrinciplesTechniquesAndTools'', a.k.a. RedDragonBook. See also GreenDragon)
* TheWizardBook (''StructureAndInterpretationOfComputerPrograms'') 
* TheRhinoBook (''JavaScript: The Definitive Guide'')
* TheOwlBook (''MasteringRegularExpressions'')
* BlueBook/PurpleBook (''SmalltalkTheLanguageAndItsImplementation'')
* CamelBook (''ProgrammingPerl'')
* TheOrangeBook (''TrustedComputerSystemEvaluationCriteria'')
* TheWhiteBook (KernighanAndRitchie's ''The C Programming Language"'')
* PickAxeBook (''ProgrammingRuby'')
* RugBook (''ForeshadowingTwentyFirstCenturyArt'' by ChristopherAlexander) [OK, this isn't computer science, though many in the DesignPatterns community have adopted ChristopherAlexander as an honorary member...]
* ThePlatypusBook (''An Introduction to Object-Oriented Programming'' by TimBudd)

Many of these books are published by OreillyAndAssociates, which tends to adorn the covers of its books with random animals.  Sometimes the critter on the cover makes sense, as in ThePythonBook (which is about PythonLanguage). Other times, there is no discernible reason for the critter in question.

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.