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