\begin{tikzpicture}[
  plain/.style = {
    draw=none,
  },
  fill opacity = 0.5,
]
  \coordinate(first) at (0,0);
  \coordinate(second) at (45:2cm);
  \coordinate(third) at (0:2cm);

  % CS, IS, and ICT circles
  \fill[red] (first) circle (1.5cm);
  \fill[green] (second) circle (1.5cm);
  \fill[blue] (third) circle (1.5cm);

  % CS, IS, and ICT labels
  \node[plain, below=0pt of first] (CS) {CS};
  \node[plain, above=0pt of second] (IS) {IS};
  \node[plain, below=0pt of third] (ICT) {ICT};

  % IT intersection between CS and IS
  \clip (first) circle (1.5cm);
  \fill[white, fill opacity=0.75] (second) circle (1.5cm);

  % IT label
  \node[plain] at ($ (CS) !.5! (IS) $) {IT};
\end{tikzpicture}