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