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