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