Each splitter need power

NO -Just one Power source to power the LNB- Follow the RED line to port 1 of the power passing port.

 

It's not the splitters that are being powered. It's the LNB (or the multiswitch) that needs power. In the case of the diagram, it's the SWM13 that needs to be powered. The path that is connected to the power inserter must pass through the red port (power passing port) on all of the splitters between the power inserter and the LNB. Since the 8 way splitter on the right side of the diagram is not part of the power inserter to LNB path, it doesn't matter what you do with the red port on that splitter (of if you use it at all).