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