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