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