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