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