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