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