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