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