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