The full-blown Squash 57 rules are available here: http://www.worldsquash.org/squash-57/squash-57-rules/

The poster version can be found here: http://www.worldsquash.org/57-rules-poster/

Some videos can be found here http://www.worldsquash.org/introductory-video/ and http://www.worldsquash.org/squash-57-knowledge-library/