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