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