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