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