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