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