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