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