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