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