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