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