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