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