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