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