Might be too late to offer my advice but it's simple, screenprinting would be the easiest, mask and ink (keep in mind compatibility with the kite material and solvents), airbrushing with a permanent fabric paint. There's plenty of options. 3M make some impressive Self adhesive films that would work perfectly.
My advice is contact a trade qualified Signy or Airbrush artist in your area. That or ship the kite to me and ill sort it out in my workshop
