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