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