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