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)(13,14,18,19,17,20,15,22)(16,21,25,26,24,27,23,28)(5,7,8,12)(6,9,10,11)(13,15,17,18)(14,19,20,22)(16,23,24,25)(21,26,27,28)(2,4)(7,12)(9,11) involution — undirected(6,10)(9,11)(14,20)(16,24)(19,22)(23,25) involution — undirected(13,16,18,25,17,24,15,23)(14,21,19,26,20,27,22,28)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.