Are there any pre-Talmudic recordings of the teachings of the 7 Noahide Laws?
I understand all 7 are found in Genesis but what is the earliest record of a structured idea of these 7 being necessary for gentiles?
The Tosefta is a compilation of the Jewish oral law from the late 2nd century, the period of the Mishnah. Tosefta Avoda Zara 9:4 describes six of the seven Noahide laws
על שבע מצות נצטוו בני נח על הדינין ועל עבודת כוכבים ועל גלוי עריות ועל שפיכות דמים ועל הגזל ועל אבר מן החי
The gemara in Sanhedrin 56a quotes this Tosefta (but lists seven, adding the prohibition to curse the name of God), then proceeds to add to them and to source their origin in Bereshit (translation: R Steinsaltz)
Since the halakhot of the descendants of Noah have been mentioned, a full discussion of the Noahide mitzvot is presented. The Sages taught in a baraita: The descendants of Noah, i.e., all of humanity, were commanded to observe seven mitzvot: The mitzva of establishing courts of judgment; and the prohibition against blessing, i.e., cursing, the name of God; and the prohibition of idol worship; and the prohibition against forbidden sexual relations; and the prohibition of bloodshed; and the prohibition of robbery; and the prohibition against eating a limb from a living animal.
So I think the Tosefta above is the first source in pre-Talmudic material.