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