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