private Set<String> botoesOn;

if(botoesOn.contais("botao1"){
    botoesOn.remove("botao1");
}
else{
    botoesOn.add("botao1");
}

protected void onPause(){
    super.onPause();
    SharedPreferences prefs =  PreferenceManager.getDefaultSharedPreferences(ths);
    prefs.edit().putStringSet("botoes", botoesON).apply();
}

botoesOn = new HashSet<String>();
botoesOn = PreferenceManager.getDefaultSharedPreferences(this);
botoesOn = prefs.getStringSet("botoes", null);

if(botoesOn != null){
    if(botoesOn).contains("botao1){
        // colocar botao1 ON
    }
    if(botoesOn).contains("botao2){
        // colocar botao2 ON
    }
    if(botoesOn).contains("botao3){
        // colocar botao3 ON
    }
    ... //Repetir para todos os botões
    ...
}