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