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