I'm assuming  that you have tried the soap and water. But I have used the cornmeal with good success, but you need a lot. Depending on the leather finish, I'd recommend the Tannery Leather cleaner or the Fiebings saddle soap which I have also used. The Tannery cleaner was great on my leather coat.Follow these steps to remove coffee stains from Leather and Suede:
  • Carefully blot up excess liquid.
  • Mix a solution of mild soap in lukewarm water.
  • Swish to create a great volume of suds.
  • Apply only the foam with a sponge.
  • Wipe dry with a clean dry cloth.

If an oily stain remains:

  • Powder the stain with an absorbent such as cornmeal.
  • Give it plenty of time to work.
  • Gently brush it off. Repeat if necessary.
  • On leather only, follow with Tannery Vintage Leather Cleaner & Conditioner or Fiebings Saddle Soap to condition the leather. (If coffee contained cream and any greasy stain remains, follow procedures to Remove Milk and Cream.)