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)(13,14,17,18)(15,19,23,22)(16,24,25,20)(21,27,28,26)(1,2,4,3)(5,6)(7,10)(8,9)(11,12)(13,15,17,23)(14,19,18,22)(16,21,25,28)(20,26,24,27)(6,9)(10,11)(13,16,17,25)(14,20,18,24)(15,21,23,28)(19,26,22,27)(5,7,8,12)(6,10,9,11)(14,18)(15,22)(19,23)(20,24)(21,27)(26,28)(1,3,4,2)(15,23)(19,22)(21,28)(26,27)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.