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