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