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