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