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