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