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