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