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