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)(13,14,19,25,18,22,17,23)(15,20,27,16,21,28,24,26)(5,6)(7,11)(8,10)(9,12)(13,15,18,21)(14,16,22,26)(17,27,19,24)(20,23,28,25)(2,4)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,25)(17,24)(18,21)(19,27)(22,28)(23,26) involution — undirected(7,12)(9,11)(13,16,19,28,18,26,17,20)(14,21,25,24,22,15,23,27)(6,10)(9,11)(14,22)(15,21)(23,25)(24,27) involution — undirectedA 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.