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