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