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