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