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