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