This would mostly be a cosmetic change in the game.
Add a number of icons that can be overlaid on the Overview or otherwise on any given colonist, to allow players to identify quickly which role they have decided they want that colonist to play, without reevaluating their skills. Especially with higher populations this will be very useful, with a high payoff for implementation difficulty.
Icons could be simple things like a gun, a leaf, a hammer, a flexing-bicep-arm, a speech bubble, a shovel, a frying pan, a chef's hat, a graduation-cap with tassel, a bow-and-arrow, a butcher's knife, a police badge, a red cross, etc.
Just add several colorings of each of the above and you've got a ton of icons without much extra work. I'd be willing to do artwork for it, even, but I don't know how to do vector artwork :P.
Another thing along these lines that would be AMAZING: Once you have colonists displayed at the top of the screen like in EdB's interface mod, below each colonist have three tiny icons indicating their top/best 3 skills, sorted left to right.
iirc, in the overview panel high leveled skills slowly becomes golden in color, while low level skills are darker. this is what i usually scan for when figuring out what each person do and what they're good at.
I guess mostly I'm going for something that is much faster to interpret visually. At the moment I just nickname everyone something relevant to what they do, but if I could, in a few seconds, get a full analysis of which jobs/roles I have filled, I'd spend much less time with the game paused just scrolling through my colonists. Often my colonists aren't particularly amazing at anything just yet and I still want to make them focus.
I just made a mod that should cover what you were asking for, adding badges to the colonist portraits.
(https://i.imgur.com/zJ32ZM9.png)
https://ludeon.com/forums/index.php?topic=48461.0 (https://ludeon.com/forums/index.php?topic=48461.0)