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