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