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