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