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)(15,22)(16,21)(17,19)(18,23)(20,25)(24,27)(26,28) involution — undirected(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15,16,23)(14,18,21,22)(17,24,25,28)(19,26,20,27)(2,4)(14,19)(17,25)(18,26)(20,21)(22,27)(24,28) involution — undirected(6,11)(7,12)(14,20)(17,25)(18,27)(19,21)(22,26)(24,28) involution — undirected(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.