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