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