Have a look on the below python script to take snap of FB homepage by using selenium package of Chrome web driver.
Script:
import selenium
from selenium import webdriver
import time
from time import sleep
chrome_browser = webdriver.Chrome()
chrome_browser.get('https://www.facebook.com/') # Enter to FB login page
sleep(5)
chrome_browser.save_screenshot('C:/Users/user/Desktop/demo.png') # To take FB homepage snap
chrome_browser.close() # To Close the driver connection
chrome_browser.quit() # To Close the browser