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