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