Green: International UNIX Environments, probably part of POSIX or The X/Open Guide.

Orange: Trusted Computer System Evaluation Criteria, part of the Rainbow Series published by the US DoD.

Pink: The Peter Norton Programmer's Guide to the IBM PC (Peter Norton wears a pink shirt in the cover photo, as can be seen in this Wikipedia article).

The devil book, The Design and Implementation of the 4.3BSD Unix Operating System by Samuel J. Leffler, Marshall Kirk McKusick, Michael J. Karels and John S. Quarterman.

The dragon book, Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Monica S. Lam, Ravi Sethi, and Jeffrey D. Ullman. (People who read the dragon book before 1986, or who were told about it by someone who did, would recognise Principles of Compiler Design as the dragon book instead. The dragon’s colour is used to distinguish the various incarnations of the book: the 1977 edition is the green dragon book, the 1986 edition seen in the film is the red dragon book, the 2006 second edition is the purple dragon book.)

Red: Trusted Network Interpretation of the Trusted Computer System Evaluation Criteria, also part of the Rainbow Series.