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