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