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