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