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