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