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