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