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