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