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