There are many different type of ratsnakes out there, what you found looks mostly like a black rat (grey rats tend not to get as long) which do vary in color from gray with brown/yellow/black saddles to solid black with white bellies, all depends on where they are found and the genetics being passed around in that location.
All ratsnakes look nearly identical as babies, light background color with darker saddles. Yellow rats (Pantherophis obsoleta quadrivittata) are a dirty yellow color with darker lines running from head to tail and are often considerably more aggressive then blacks. Red ratsnakes (Pantherophis guttatta) are also known as cornsnakes and are probably the #1 pet snake out there and are often rather docile even in the wild. Great plains or emorys ratsnake is like a greyer smaller version of a corn, Everglades rats are like an orangy yellowy version of a yellow rat. Grey rats are smaller and grayer then black rats, Texas rats out west are huge brown and often nasty, along with a few other much less common species out west.