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