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