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