org-property-format

org-property-format is a variable defined in `org.el'.
Its value is

"%-10s %s"

Documentation:
How property key/value pairs should be formatted by `indent-line'.
When `indent-line' hits a property definition, it will format the line
according to this format, mainly to make sure that the values are
lined-up with respect to each other.

You can customize this variable.