Yes, of course, depend on the strength the painting is different.
I want to control from the arduino board the strength to press the spray.
I don't know how can i make something to push the spray's head (button)
I assume then that the 'spray button' has a finite travel range that causes it to travel through full off, some variable spray to full spray? So it would seen that you just need to mechanically couple a servo arm such that you can manipulate the spray buttons travel range via the specific servo position. Your servo must also have a torque rating high enough to overcome the force/friction of the button and cause this travel, via the servo's basic torque rating and/or by using mechanical leverage linkage such that the desired travel and torque requirements are both met.