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