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