most small machines are fairly loud, normally i find that the pump is a fair bit quieter when under "load" that is when you are making the coffee. But will be loud when just pumping water out the Grouphead
as for making it quite. you could try changing the surface the machine sits on. eg on a tea towel, or a chopping board wood / plastic. even a tray might make a diff. Some surfaces seem to increase or decrease some noise. I assume it is on rubber feet already
other mods could be looked into, is the pump "rubber mounted" or surrounding it in a box inside the machine (rubber roll?) But then you may encourage other problems like heat / moisture issues? and there may not be room inside the box.
good luck on your coffee journey :)