Windows: C:\Users\YOUR_USER_NAME\AppData\LocalLow\Sinister Design\Telepath Tactics Liberated
YOUR_USER_NAME is whatever your user name is for Windows.
The file names look like savedGame1.telepath; the number should correspond to the save slot you're using for your game. (You may also see files like savedGameBS1.telepath--these are "battle start" saves used to restart battles from the beginning.)