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