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