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)(11,16)(12,14)(13,15)(17,18,21,23)(19,24,22,20)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,38)(37,40)(2,6)(4,7)(9,11)(10,15)(12,16)(13,14)(17,18)(19,20)(21,23)(22,24)(25,26,29,32)(27,30,35,33)(28,31,37,40)(34,38,36,39)(1,3)(2,7)(4,6)(5,8)(9,10,14,12)(11,16,13,15)(17,19,21,22)(18,20,23,24)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,38)(37,40)(1,3)(2,4)(5,8)(6,7)(9,12,14,10)(11,16,13,15)(17,18)(19,20)(21,23)(22,24)(25,27)(26,30)(28,36)(29,35)(31,39)(32,33)(34,37)(38,40)(1,4)(2,8)(3,6)(5,7)(9,13,14,11)(10,15,12,16)(17,20)(18,22)(19,23)(21,24)(25,28,29,37)(26,31,32,40)(27,34,35,36)(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.