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