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