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