How to save the 'PlotFcn','pswplotbestf' image for ParticleSwarm function

Hi everyone, I'm working on my master thesis and I'm using my university cluster. I run my code (an optimization code using the ParticleSwarm function) and I'd like to save the relative image (the simil-hyperbola one than the code gives me back with the iterations number on the x-axis and the objective funcion on the y-axis). I've tried to save it as a normal image (eg, saveas...) but it didn't work. Do you have any suggestion?

Best, Luca