True, there should be a way to change the preset faces you can choose from. I thought you meant alter the already chosen players face.
There is, and you can.. just not a direct edit like you can with NPCs. As deepside0 said, it's based on the race that you've chosen for your player. To make a preset face, set the 'Is CharGen Face Preset' checkbox on an NPC who's face you want to use, then Character-->Update FaceGen Model Availability and save the mod. If the NPC is the same race as your player, the new face will be selectable for use in the players race menu.. If the race is different, it won't appear unless you change players race to the same. There are no options for body customization other than what they wear. I recently changed my players race from caucasian to a raider and found all the presets I had made previously for raiders.