I don't have a OnePlus One, so take this answer with a grain of salt.
Make sure you are installing the .zip and NOT the .img factory image file from Color OS's recovery mode.
If that doesn't work, you might want to try one of the nightly builds to see if it works instead.
If you STILL do not have success, you may want to try installing with fastboot instead of the .zip-- note that this will require the .img factory image file, not the .zip file. The steps for fastboot mode on the OnePlus One are: 1. Turn the phone off. 2. Hold volume up + power until the "fastboot" screen appears.
You can read more about using fastboot at the cyanogenmod wiki: wiki.cyanogenmod.org/w/Fastboot
To ensure a smooth boot after you flash the new system, don't forget to do a "factory reset" to erase all the previous personal data when switching OSes... that is an option that should be available somewhere in the recovery mode. Good luck!