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