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