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