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