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