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