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