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