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