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