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