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