Studs are normally vertical 2 x 4's placed every 16" on center. There might be some places where the plans would help, like ceilings, but a lot of plans only indicate using this standard practice. But you don't need them anyway. Most tape measures have the 16" stud centers indicated. Start by measuring the probable stud locations by using the tape from an outside wall. Then drill a hole at the measured probable location and around 4 feet up. If you did not hit a stud, then take a coat hanger with the kinky parts cut off and bent into a curve and probe thru the hole to find the edge of a stud. When you have found the stud edge inside the wall, pull out the coathanger and try to approximate how you were holding it outside the wall. Add 3/4" to get to the stud center (half of a nominal 2 x 4's actual 1-1/2" dimension) and drill another hole. You shold now have found the stud location.
This is harder to describe than to do but a house built in 1957 would follow the same "rules" used today for stud wall construction. My daughters house, built in the 1840's, follows none of them but we can still use this general method. If you try to think how the person who did your wall framing did, you should be able to guess the stud locations very closely.