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