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