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