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