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