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