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