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