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