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