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