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