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