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