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