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