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