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