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