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