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