1. Be exceptionally nice and polite. I mean lay it on thick.
2. Ask that if her employee was uncomfortable with orange shirts, would she be asking you to not wear an orange shirt? Ask her what is more important to her, her employees feeling "comfortable" with every customer that comes into the store, or making sales to customers? Explain that you are a law abiding citizen who cares enough about yourself and those around you to have the means available for protection in case a serious, violent crime should occur and there should be no more reaction to a lawfully carried and possessed firearm than a lawfully worn orange shirt.
3. Explain that a no guns policy is going to do absolutely nothing to keep a criminal from bringing a gun into the store. That's the definition of a criminal - one who does not obey laws, rules or store policies. The only thing a no guns policy is going to do is keep paying customers out of the business.
4. Ask her why she feels the need to drive away perfectly legal customers who want to spend money in their store. You don't smell. You don't make obnoxious noise. You don't invade anybody's space. All you do is buy food in her store, contributing to profits, and eat there. The gun on your belt is no different than a cell phone (except your gun is less annoying, it doesn't make distracting noises). Ask her why she doesn't explain to her employees that you a perfectly legal customer who is only concerned about his own safety instead of running off paying, law abiding customers.
5. Ask her in today's economy, full of unemployment, which she thinks would be easier to replace.... a law abiding, paying customer.... or an employee who has problems with law abiding, paying customers.
Always remember suggestion number 1. Even if she is a complete and total anti with no common sense whatsoever and pushes every button you have - when you call her, you are representing the gun owner's of America. If you lose it with her, you are going to affirm every false belief she has about us.
You might want to ask her which coffee store is doing better - Peets Coffee that bowed to the Brady Campaign, banned guns, and saw a 25% jump in profits,or Starbucks Coffee which stood firm and allows guns in their stores and saw a 100% jump in profits.