Platforms like Dr-Bios.com host specific requests for these files, though some may require a premium account.
For free schematic downloads, Elektrotanya often provides PDF versions of the 2012 S-Series schematics. Essential Tools for Viewing Files hp probook 4540s boardview link
You can access the circuit diagrams for the HP ProBook 4540s Platforms like Dr-Bios
motherboard, you generally need two types of files: the (circuit diagram) and the Boardview (physical layout). hp probook 4540s boardview link