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