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