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)(25,26,31,28)(27,33,35,29)(30,36,38,32)(34,37,40,39)(3,7)(5,8)(9,10,14,12)(11,15,18,17)(13,16,21,20)(19,22,24,23)(25,27,31,35)(26,29,28,33)(30,34,38,40)(32,37,36,39)(1,2)(3,5)(4,6)(7,8)(10,12)(11,18)(13,21)(22,23)(26,28)(29,33)(30,38)(34,40) involution — undirected(9,11)(10,15)(12,17)(13,19)(14,18)(16,22)(20,23)(21,24)(25,28,31,26)(27,33,35,29)(30,36,38,32)(34,39,40,37)(1,3)(2,5)(4,7)(6,8)(9,12,14,10)(11,15,18,17)(13,20,21,16)(19,22,24,23)(25,29,31,33)(26,27,28,35)(30,37,38,39)(32,34,36,40)(1,2)(3,5)(4,6)(7,8)(9,13)(10,16)(11,19)(12,20)(14,21)(15,22)(17,23)(18,24)(25,30,31,38)(26,32,28,36)(27,34,35,40)(29,37,33,39)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.