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