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