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