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