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)(17,18,21,20)(19,23,24,22)(25,26,29,30)(27,33,34,31)(28,36,37,32)(35,38,40,39)(2,5)(6,7)(9,11)(10,12)(13,14)(15,16)(17,18,21,20)(19,22,24,23)(26,30)(27,34)(28,37)(38,39)(3,8)(6,7)(11,14)(12,16)(17,18,21,20)(19,22,24,23)(25,26)(27,33)(28,32)(29,30)(31,34)(35,39)(36,37)(38,40)(1,3,4,8)(2,6,5,7)(9,12,13,16)(10,14,15,11)(17,19,21,24)(18,22,20,23)(25,27)(26,31)(28,35)(29,34)(30,33)(32,38)(36,39)(37,40)(1,2)(3,6)(4,5)(7,8)(9,10)(11,16)(12,14)(13,15)(17,20,21,18)(19,23,24,22)(25,28,29,37)(26,32,30,36)(27,35,34,40)(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.