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