Many code editors/IDEs have a feature that will highlight pairs of { } when placing the text cursor next to one of them. This can help you see what code belongs to loops and other block scopes, but otherwise you'll go a long way with just proper indentation.
I'm not sure that you will find any editor that directly colourises a loop structure. What would it do if you had nested loops?
Highlighting matches braces is useful, and also helps with scope. But "loop" covers many flow-control routes, many not trivial: e.g. exiting them with break or return, recursion, or when (heaven forbid) someone is using goto to create an implicit loop structure.
Get used to using good indentation. (Actually, I quite like python's reliance on it for establishing good practice.)
you can sort of force it with notepad++ and your own language, but nesting would be frustrating.
you can also perhaps practice your own form of defensive coding, eg I have been known to do this to improve readability if my code gets complicated:
1 2 3 4 5 6 7 8 9 10 11
for(int i...)
{
for(int j...)
{
for(int k..)
{
}//end for k
}//end for j
}//end for i
your IDE should tie pairs together, and indentation should make it clear, but even so, running across a random } while browsing it really helps to have a what is this comment for long blocks.
Many modern IDEs have "folding" options and will show the beginning and end of the loop structure along the left side of the window... This works even with nested structures.