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