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