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