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