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