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