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