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