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