from PIL import Image
...
d.save_screenshot('xx.png')
element = d.find_element_by_xpath("//div[contains(@class,'shumei_captcha_wrapper')]")
print(element.location)                # 打印元素坐标
print(element.size)                    # 打印元素大小

left = element.location['x']*1.25
top = element.location['y']*1.25
right = element.location['x']*1.25 + element.size['width']*1.25
bottom = element.location['y']*1.25 + element.size['height']*1.25

im = Image.open('xx.png')
im = im.crop((left, top, right, bottom))
im.save('yy.png')