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