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