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