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