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