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