You can use a 40 60 pressure switch instead of a 30 60 pressure switch although you may need to adjust the pressure switch to your proper pressure for shut off and turn off.
A 40 50 pressure switch can be adjusted to work for 30 50 pressure.
If not adjusted the 40/60 pressure switch will turn the pump on at 40 PSI and turn the pump off at 60 PSI.
A 30/50 pressure switch turns the pump on at 30 PSI and off at 50 PSI.
If you're using the pressure switch in a well system and you want to increase pressure at shut off and turn off you also need to ensure that your well pressure tank is at the proper cut off pressure and ensure that your well pump can build up to the 60 PSI to shut off the switch.
If your well pump can only build up to 50 PSI then using a 40/60 pressure switch that is not adjusted will not let the pump turn off as the pump won't be able to build up to the 60 PSI to cut the pump off.
However if you adjust the 40/60 pressure switch to cut off at 50 PSI and cut on at 30 PSI then it will work just fine.
Adjusting a pressure switch is pretty easy.
Have the pump turn on and then while the pump is on and no water is flowing and it's trying to build up pressure turn the middle nut on the well pressure switch or pressure switch counterclockwise until the pump shuts off.
That will then be the pressure that the switch will shut off.
If you're not comfortable with adjusting the pressure switch then you should just use the proper pressure switch but they aren't all that hard to adjust.