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