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)(13,16,18,23)(14,19,15,21)(17,26,25,24)(20,28,22,27)(1,2)(3,4)(13,17,18,25)(14,20,15,22)(16,24,23,26)(19,27,21,28)A 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.