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