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