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