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