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