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