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