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