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