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