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