The passage you're after is in the Hesiodic Theogony, lines 501-506, dating to around 700 BCE (so one of the very earliest extant pieces of Greek poetry).

And he freed from their deadly bonds his father's brothers,
Sky's sons, whom their father had bound in his folly.
And they repaid him in gratitude for his kind deed,
giving him the thunder and the blazing thunderbolt
and the lightning, which huge Earth had concealed before.
Relying on these, he rules over mortals and immortals.

Your difficulty in finding the passage may have been partly due to the fact that the text doesn't use the names "Zeus" or "Cyclopes" at this point. The identification relies on lines 139-141, where the Cyclopes are named as forging the thunder and thunderbolt for Zeus.

There's no particular reason to suppose that any symbolism is intended by the poet, or built into the material. Even if there were, there'd be no single authoritative interpretation: the significance is open. There is no word for "magic" in Greek of this era. If there is a symbolism, it would likely be tied up with the Hundred-Handers, or Hekatoncheires, since they and the Cyclopes are grouped together with detailed descriptions in the earlier passage.