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