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