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