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