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