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