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