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