Unless you find one that is set up for tours like mentioned in an earlier post, you won't find any dairy farms opening their doors for you to look around.
If you noticed in the earlier post about the one that does conduct tours you get to "drive" thru the milking barn.
Farms where animals are involved are VERY strict about people traipsing thru their farms due to disease issues and cross contamination of the diseases even from neighboring farms.
Hog farmers go one step further to prevent disease and have all visitors/traffic stop at the end of their driveway and can not come any further.
Trust me you are not missing anything by not seeing an actual dairy farm operation up front and personal. You most likely would not like observing how it is actually done anyway. I know I didn't once I got to see it. :(