Roughly this, a few are wrong like say greninja having white cheeks. For the most part you'll know its shiny because:
A) It shines
B) A soundbyte plays with a twinkle
C) Its not even remotely similar to the original, enough that you should be able to tell its shiny. (C doesn't include Garchomp, that shit is ass)
D) On the summary if you caught it, there would be a red shape instead of a blue.
E) The ground rustles and shines and twinkles if you find a shiny with pokeradar.
Basically what I'm saying is you don't need the image of all the shinies but here it is. Also a few not all in 3d.
http://imgur.com/a/VZ0jQ 