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