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