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)(6,9)(8,12)(10,11)(13,14)(15,22)(16,19)(17,23)(18,21)(20,24)(25,26)(27,28) involution — undirected(1,2,3,4)(13,15,22,14,18,19,16,21)(17,25,28,27,26,23,24,20)(6,10)(9,11)(13,16,18,22)(14,19,21,15)(17,24,26,28)(20,25,27,23)(7,12)(9,11)(13,17,22,28,18,26,16,24)(14,20,19,25,21,27,15,23)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.