The formula δώρων γραφή, "indictment for bribes," may have been presented in the lesson that contains this exercise, Jorsay. So the last part of the sentence would read, "to indict for bribes every one of (σύμπαντας) the public speakers who have been stealing." Note that γραψόμεναι is a future middle participle, expressing purpose (as the future participle often does).