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