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