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