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