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