customise bibliography style of multi bibliography

Question

I have two bibliographies in my document. I am using multi bib. I displayed the two bibliographies in two separate list using the following code. But I need to customise the citations of one of them to be [S1] and the other one to be numeric citaton [1]

% arara: pdflatex
% arara: bibtex: { files: [ mydoc, PS ] }
% arara: makeindex
% arara: pdflatex
% arara: pdflatex

\documentclass{article}
\usepackage{multibib}
\newcites{PS}{Primary Studies}

\usepackage{url}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}

\usepackage[titletoc,title]{appendix}
\usepackage{afterpage}

\begin{document}
\section{Main body text}

reference 1 [1]
primary study 1 [S1]


\bibliographystyle{IEEEtran}
\bibliography{template_latex_bibliography-bib}

\begin{appendices}
\section{List of Primary studies}
\bibliographystylePS{IEEEtran}
\bibliographyPS{mydoc-primarystudies-bib}
\end{appendices}

\end{document}