Maybe I'm not following your question**, but it should be a case of setting the Super product attributes configuration
of the Associated Products
of the Configured Product
.
So if the red t-shirt is an extra 10, then put 10 next to that option for the color attribute. (In the bit so it looks like 'Price: 10 Fixed' ). Does that make sense? Can you follow which part of the Magento Admin area I mean? It is Catalog->Manage Products->[edit your configured product]->Associatated Products->Super product attributes configuration->Color->Option:Red Price:10
Remember to save the product and then on the front end of your site in the drop down of colour options for the T-shirts you should see 'Red +10' displayed. You might need to refresh some caches.
**EDIT following comment below:
Then I think what you are trying to do is non-standard so it would need a third party module or custom coding.
One other suggestion: you might try creating bundle products instead of configurable products - on the front end the bundle options will pull through the group price of the simple product.
Have you looked at this module Customer Group Prices for Magento by Webtex? I haven't used it.
If you are planning to code something yourself let me know and I will change my answer above but I don't have a full answer for custom coding this and I don't think it will be trivial because it sounds like you want customer group level control of the Super product attributes configuration
of the Associated products
of a configurable product
type, yes? If you are looking for code tips please edit your question to list explicitly the simple product prices and your customer groups - maybe an example price/group matrix so that stackoverflow readers can understand your required product price logic.
Maybe there is another way to organize your products like using multiple stores, multiple websites or trying bundles.