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