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