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