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