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