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