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