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