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