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