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