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