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