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