I can see why you are frustrated with the repeated conversations. If it were me, I would need to include a variety of topics that surfaced during the day. But if your husband is like most men, his work defines much of who he is. Men can be consumed with it way beyond what we think is normal and acceptable. I'm not condoning it or saying that's an ok thing, but I do understand the makeup of a man and why they place so much value in who they are because of their work involvement.
I always believed the marriage relationship should take priority over jobs, but sadly that doesn't always happen.
You asked for a non-insulting way to get him to change the subject. He may not want to change at first, until he fully realizes the impact it has on you. This is where you can help him comprehend that your marriage cannot thrive within the confines of the same conversation day in and day out.
https://bit.ly/2JZnkZA Hopefully he'll pick up on the obvious and do something about it.
How about something simple like agreeing to give each other equal time for discussing topics of importance, no matter what they are. Start simple. Make a promise you will both contribute to the conversation. Maybe after a while he will see how limited he has been.
I think your husband will need a reason to want to change. And strengthening the marriage relationship is always a good reason. Find out what he's thinking, and is he aware how this topic dominates all others. I know there is a risk laying your heart on the table. You don't know what he will do with it and you don't want to get hurt. Pray and ask God to help you arrange a time when his heart will open and will really be able to hear what you are saying.