If you want the Revised Edition (the one with the famous Warren Buffett appendix and Jason Zweig’s commentary), you will need a commercial audiobook. But "free" is still possible via the model.
These are not the audiobook, but they are resources for learning the material quickly. If you only need the core lessons (Defensive vs. Enterprising investor, Margin of Safety), these podcasts are invaluable. If you want the Revised Edition (the one
Finding a high-quality, legal, and free version of Benjamin Graham's The Intelligent Investor Margin of Safety)