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