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