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