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