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