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