If your August move to CO was intended to be permanent (and it sounds like it was since you changed your drivers license and voters registration), then you would file a part-year resident tax return in each of the two states as @SundayInSalem described. CA can tax the income you earned as a resident of CA; CO can tax the income you earned as a resident of CO.
But if the move was intended to be temporary or transient, and you did not abandon your domicile in CA while living in CO, then you would file a non-resident return in CO and a resident return in CA. In that situation CO could tax the income you earned by working in CO, and CA could tax ALL your income, including what you earned in CO. But CA would let you take a credit for the taxes paid to CO.
You'll find CA's detailed rules on residency in this reference:
https://www.ftb.ca.gov/forms/2020/2020-1031-publication.pdf
In particular, you should read "Change of Domicile" on page 10.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
