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