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