The National Library of Australia (of all places) has an electronic version of an 1884 publication from the Oxford Historical Society, entitled "Old Plans of Oxford". It includes Agas' 1578 map of Oxford (mentioned by sempaiscuba in the comments), on which Canterbury College can be found. Here's an extract from Panel II:
This appears to be approximately here on Google Maps:
Note that South appears to be at the top of Agas's map.