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