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