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