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