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