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