If you are designing Public, Private or Hybrid Cloud based on Windows Server 2012 and System Center 2012 SP1 this set of documents will be very useful for a starting point. They will offer you the basics you will need in order to design your Cloud and take the necessary decisions. Download all 4 documents from here.
Here are some free SCCM 2007 Visio Stencils published by Jawad Qazi on the Technet Gallery.
The Microsoft Private Cloud Fast Track Program is a joint reference architecture for building private clouds, which combines Microsoft software, consolidated guidance, and validated configurations with hardware partner computing power, network, and storage architectures; and value-added software components.
The provide documents can be very useful in designing Private Cloud Solution based on System Center 2012:
Microsoft has release the final version of Design and Planning Guide for SCOM 2012. This guide can help you in implementing SCOM 2012 or updating from SCOM 2007. Download and more information on the link below.