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