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