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