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