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