I'm not sure about the ground idea.
this is how I am wired and it matches the schematic you linked earlier
x axis=
PUL+ to 5 volt power supply
PUL- to P2
DIR+ to 5 volt power supply
DIR- to P3
ENABLE to 5 volt power supply
Y axis=
PUL+ to 5 volt power supply
PUL- to P4
DIR+ to 5 volt power supply
DIR- to P5
ENABLE to 5 volt power supply
Z axis=
PUL+ to 5 volt power supply
PUL- to P6
DIR+ to 5 volt power supply
DIR- to P7
ENABLE to 5 volt power supply