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