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