You are allowed by Colombian law to drive with a US license as much as you want as long as your license is valid and not expired. I have been driving with mine for the last 3+ years, been pulled over a few times, and had never been questioned about it. I don't have a Colombian license and I'm not planning to get one. I could even register my car to my name with my US license.
Go to the Secretaria de Transito en your municipality. Take your US license along with you. When it's your turn at the window, explain that you would like to use your US license to apply for a Colombian one. You will probably be told that you will need to a take a 40-hour driving course. If that happens, ask for a waiver. That happened when I applied for mine. I spoke to the Director, and he waived the driving course, but it cost me a 120 mil "fee." He arranged for me to get the required driver education certificate. I also needed to go down the street for a driver physical which consisted of an interview with a Dr, hearing test, eye exam and a coordination test. That cost me 40 mil. I had to return to the S de T with my medical certificate, get fingerprinted, and paid around 100 mil for the license. In the meantime, the director obtained my driver education certificate. My license was ready for pick-up a week later. My license is valid for 3 years.