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