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