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