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