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