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