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