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