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