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