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