Snackbar snackbar = Snackbar.make(findViewById(R.id.main_content), "TEST", Snackbar.LENGTH_INDEFINITE);
View snackbarView = snackbar.getView();
// change background color of snackbar
snackbarView.setBackgroundColor(ContextCompat.getColor(this, R.color.my_color));

// align text to right end and add image icon to left
TextView textView = (TextView)snackbarView.findViewById(android.support.design.R.id.snackbar_text);
textView.setTextSize(16);
textView.setGravity(Gravity.END | Gravity.CENTER_VERTICAL);
textView.setCompoundDrawablesWithIntrinsicBounds(R.drawable.icon_test, 0, 0, 0);
snackbar.show();