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