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