It uses an ABAB rhyme scheme within each stanza, which means that the first and third lines rhyme, and the second and fourth lines rhyme.
Here's an example from the first stanza:
> Burning bright, the forests of the night;
>
> What immortal hand or eye,
>
> Could frame thy fearful symmetry?
>
> In what distant deeps or skies.
This consistent rhyming pattern adds to the poem's rhythm and musicality.