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