  We describe a simple way to write down explicit derivations of octonions that
form a Chevalley basis of $\mathfrak{g}_2$. This uses the description of
octonions as a twisted group algebra of the finite field $\mathbb{F}_8$.
Generators of $\operatorname{Gal}(\mathbb{F}_8/\mathbb{F}_2)$ act on the roots
as $120$-degree rotations and complex conjugation acts as negation.
