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