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