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