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