One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7)(3,6,4,8)(9,10,12,13)(11,14,15,16)(17,18,20,22)(19,21,23,24)(25,26,30,35)(27,36,38,33)(28,31,37,40)(29,32,39,34)(1,3,5,4)(2,6,7,8)(10,13)(14,16)(17,19)(18,21)(20,23)(22,24)(25,27,29,28,30,38,39,37)(26,31,34,36,35,40,32,33)(1,4,5,3)(2,6,7,8)(10,13)(11,15)(19,23)(21,24)(26,32)(27,37)(28,38)(29,39)(31,40)(34,35)(9,11,12,15)(10,14,13,16)(25,28,39,27,30,37,29,38)(26,33,32,40,35,36,34,31)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.