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