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