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