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