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