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