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