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