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