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