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