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