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