@OneOverTwo  

 
Yep; the easiest way to tell was to compare the yellow highlights in her hair/mane to her skin/coat; as a pony her coat was darker, and as a human her hair was darker.
 
All we really had to show for that in non-night colors was this thing from the Gameloft app:
 

 
This; in a period where there were no other fanmade vectors of her to take and use like how it is nowadays, which I guess is where the vector artists got most of their colors from. I can really only think of maybe two or three artists off the top of my head that don’t just use her skin and hair color for her pony form, but it makes sense why.

@Ebalosus  
OMG, she better give Twilight’s crown back.

@Background Pony #9937  

+1 to that, my friend.

@thps48  
Judging by all the other pony to human colour differences it should be slightly darker coat on a pony compared to skin on a human.

@OneOverTwo  
I guess. Since she’s only a pony for around two minutes while on-screen at night, we usually assume her coat and mane colours are equivalent to her skin and hair. :T

@OneOverTwo  
*Hasbro’s

@Background Pony #6FF1  
I have that toy, but ever since I started collecting Transformers I’ve learned that I can’t trust the colouration of Hadbro’s toys to tell me the right details.

We need to see Sunset in her pony form again  
I don’t even care how, it just needs to happen

@OneOverTwo  

@thps48  
The thing about that is I can’t trust that those are her actual canon colours what with them being fan made & all.

@SeraphimDawn  
Chamon! X3

She was BAD!

@OneOverTwo  
Just look up fan made Pony Sunset vectors. X3

Wish we could see this form in decent lighting.