One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(5,6,8,10,9,11,7,12)(13,14,16,20,18,22,17,21)(15,19,24,27,25,28,23,26)(2,4)(13,15,18,25)(14,19,22,28)(16,24,17,23)(20,27,21,26)(5,6)(7,10)(8,12)(9,11)(14,20)(15,23)(16,17)(21,22)(24,25)(26,27) involution — undirected(2,4)(5,7,9,8)(6,10,11,12)(13,16,18,17)(14,21,22,20)(15,24,25,23)(19,26,28,27)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.