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