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