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