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