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