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