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