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)(15,25,17,21)(16,18,24,20)(22,26,27,28)(1,2)(3,4)(6,10)(11,12)(13,15,19,17)(14,21,23,25)(16,27,24,22)(18,26,20,28)(5,7,9,8)(6,11,10,12)(13,16,20,14,19,24,18,23)(15,25,26,22,17,21,28,27)(2,4)(13,17,20,28,19,15,18,26)(14,22,24,21,23,27,16,25)(5,8,9,7)(6,11,10,12)(13,18,19,20)(14,16,23,24)(15,26,17,28)(21,27,25,22)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.