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