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