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