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)(25,26,29,31)(27,32,35,30)(28,36,38,33)(34,39,37,40)(1,2)(3,4)(5,7)(6,8)(9,11,15,12)(10,16,14,17)(13,19,21,20)(18,23,22,24)(25,27,29,35)(26,30,31,32)(28,34,38,37)(33,39,36,40)(1,3)(2,6)(4,7)(5,8)(26,31)(30,32)(33,36)(39,40) involution — undirected(1,3)(2,4)(5,8)(6,7)(9,12,15,11)(10,17,14,16)(13,19,21,20)(18,23,22,24)(25,26)(27,30)(28,33)(29,31)(32,35)(34,39)(36,38)(37,40)(1,4,5,6)(2,3,7,8)(9,13,15,21)(10,18,14,22)(11,19,12,20)(16,23,17,24)(25,27)(26,32)(28,37)(29,35)(30,31)(33,39)(34,38)(36,40)(1,3)(2,4)(5,8)(6,7)(9,14,15,10)(11,17,12,16)(13,18,21,22)(19,23,20,24)(25,28)(26,33)(27,34)(29,38)(30,39)(31,36)(32,40)(35,37)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.