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