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