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