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)(15,24)(16,26)(17,22)(18,20)(19,23)(21,27)(25,28) involution — undirected(1,2)(3,4)(6,9)(10,12)(13,15,17,26)(14,16,22,24)(18,25,19,21)(20,27,23,28)(5,7,8,11)(6,10,9,12)(14,20)(15,25)(18,19)(21,26)(22,23)(27,28)(2,4)(13,16,17,24)(14,21,22,25)(15,20,26,23)(18,28,19,27)(6,9)(10,12)(14,22)(16,24)(20,23)(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.