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