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