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