how to connect the hx711 amplifier directly to the arduino, without to need for jumpers?
Are you asking how to permanently connect the HX711 to the Arduino instead of using jumpers ?
If so, then soldering them would seem to be a good way
I make custom cables using dupont connectors and pins. I have a nice variety of single and double row headers and connectors. I also cheat and if possible use premade cables (typically ribbon cable with 1 pin ends), remove the ends (holder) and replace with the configuration I need, it comes out looking nice.