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