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