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