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)(16,24)(17,21)(18,27)(19,22)(20,25)(26,28) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,12,11)(13,14)(15,24)(16,23)(17,21)(18,27)(19,22)(20,26)(25,28)(5,7,9,8)(6,11,12,10)(13,15,19,16)(14,20,22,28)(17,25,18,26)(21,24,27,23)(2,4)(13,16,19,15)(14,20,22,28)(17,26,18,25)(21,24,27,23)(5,8,9,7)(6,11,12,10)(13,17,19,18)(14,21,22,27)(15,25,16,26)(20,24,28,23)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.