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