How to Cite Online .pdf Publication in Article?
The URL is required, as is the date of access and the date of creation (if it's available). I don't think the colour is really a necessity; however, what does matter is that you are consistent throughout your piece of writing. I normally use dark blue or black. I try to put it with that kind of serif-y "programming language" font, e.g. using the \url{} package in LaTeX. 

The style of citation changes the way you cite electronic sources. 

For MLA:

Editor, author, or compiler name (if available). Name of Site. Version
   number. Name of institution/organization affiliated with the site
   (sponsor or publisher), date of resource creation (if available). 
   Medium of publication. Date of access.


for an entire website. The rules for MLA change slightly for other types of website citations. 

For APA:

Author, A.A.. (Year, Month Date of Publication). Article title. Retrieved from URL


for websites with a known author. For websites without an author, and other types of electronic source citations, the rules are different. 



For this website in particular, I would say it's closest to MLA-type citation but that perhaps it's missing the name of the institution that it's credited to. I haven't checked the website, so perhaps it's unavailable for some reason. Check the MLA link above to see the proper way to cite this particular PDF, as the link has multiple citation fashions which depend on the type of website / online material it is.

I think they were going for something like this (using the 'single web page' MLA):

John A. Schroeder. "System Study: Residual Heat Removal 1998–2014" 
     Idaho National Laboratory. INL, Décember 2015. 
     Web. 3 August 2016. URL: http://nrcoe.inel.gov/resultsdb/publicdocs/SystemStudies/rhr-SPAR-unreliability-external-2014.pdf


However the most important thing (second to making sure to cite, of course) is that the author is consistent throughout.



And finally, according to google scholar, the article is a 'tech report' and the BiBTeX citation is thus:

@techreport{schroeder2015system,
  title={System Study: Residual Heat Removal 1998-2014},
  author={Schroeder, John Alton},
  year={2015},
  institution={Idaho National Laboratory (INL), Idaho Falls, ID (United States)}
}