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