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