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