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