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