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