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