One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(5,6,7,8)(13,14,17,18)(15,19,23,21)(16,24,25,20)(22,27,28,26)(9,10,11,12)(14,18)(19,21)(20,24)(26,27)(5,6)(7,8)(9,10)(11,12)(13,14)(15,21)(16,20)(17,18)(19,23)(22,27)(24,25)(26,28) involution — undirected(13,15,17,23)(14,19,18,21)(16,22,25,28)(20,26,24,27)(1,3,4,2)(13,16)(14,20)(15,22)(17,25)(18,24)(19,26)(21,27)(23,28)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.