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