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