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