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