documentclass{beamer}

usepackage{graphicx}
usepackage{tikz}
usetikzlibrary{shapes,backgrounds,calc}


% http://tex.stackexchange.com/questions/55594/tikz-two-colored-circle-split
makeatletter
tikzset{circle split part fill/.style args={#1,#2}{%
 alias=tmp@name, % Jake's idea !!
  postaction={%
    insert path={
     pgfextra{%
     pgfpointdiff{pgfpointanchor{pgf@node@name}{center}}%
                  {pgfpointanchor{pgf@node@name}{east}}%
     pgfmathsetmacroinsiderad{pgf@x}
      %begin{scope}[on background layer]
      %fill[#1] (pgf@node@name.base) ([xshift=-pgflinewidth]pgf@node@name.east) arc
      %                    (0:180:insiderad-0.5pgflinewidth)--cycle;
      %fill[#2] (pgf@node@name.base) ([xshift=pgflinewidth]pgf@node@name.west)  arc
      %                     (180:360:insiderad-0.5pgflinewidth)--cycle;
      fill[#1] (pgf@node@name.base) ([xshift=-pgflinewidth]pgf@node@name.east) arc
                          (0:180:insiderad-pgflinewidth)--cycle;
      fill[#2] (pgf@node@name.base) ([xshift=pgflinewidth]pgf@node@name.west)  arc
                           (180:360:insiderad-pgflinewidth)--cycle;            %  end{scope}
         }}}}}
 makeatother

begin{document}

begin{tikzpicture}
  tikzset{every node}{minimum size=8mm}
  node[circle split part fill={red,cyan}] (p1) at (  0:1.9) {,,,,};
  node[circle split part fill={blue,magenta}] (p2) at ( 72:1.9) {,,,,};
  node[circle split part fill={green,violet}] (p3) at (144:1.9) {,,,,};
  node[circle split part fill={green,violet}] (p4) at (216:1.9) {,,,,};
  node[circle split part fill={orange,pink}] (p5) at (288:1.9) {,,,,};

  draw (p1) -- (p2);
  draw (p1) -- (p3);
  draw (p1) -- (p4);
  draw (p1) -- (p5);
  draw (p2) -- (p3);
  draw (p2) -- (p4);
  draw (p2) -- (p5);
  draw (p3) -- (p5);
end{tikzpicture}
end{document}

documentclass[tikz,border=5pt]{standalone}

usetikzlibrary{shapes}


% http://tex.stackexchange.com/questions/55594/tikz-two-colored-circle-split
makeatletter
tikzset{circle split part fill/.style args={#1,#2}{%
 alias=tmp@name, % Jake's idea !!
  postaction={%
    insert path={
     pgfextra{%
     pgfpointdiff{pgfpointanchor{pgf@node@name}{center}}%
                  {pgfpointanchor{pgf@node@name}{east}}%
     pgfmathsetmacroinsiderad{pgf@x}
      %begin{scope}[on background layer]
      %fill[#1] (pgf@node@name.base) ([xshift=-pgflinewidth]pgf@node@name.east) arc
      %                    (0:180:insiderad-0.5pgflinewidth)--cycle;
      %fill[#2] (pgf@node@name.base) ([xshift=pgflinewidth]pgf@node@name.west)  arc
      %                     (180:360:insiderad-0.5pgflinewidth)--cycle;
      fill[#1] (pgf@node@name.base) ([xshift=-pgflinewidth]pgf@node@name.east) arc
                          (0:180:insiderad-pgflinewidth)--cycle;
      fill[#2] (pgf@node@name.base) ([xshift=pgflinewidth]pgf@node@name.west)  arc
                           (180:360:insiderad-pgflinewidth)--cycle;            %  end{scope}
         }}}}}
 makeatother

begin{document}

begin{tikzpicture}
  tikzset{every node}{minimum size=8mm}
  node[shape=circle split,circle split part fill={red,cyan}] (p1) at (  0:1.9) {,,,,};
  node[shape=circle split,circle split part fill={blue,magenta}] (p2) at ( 72:1.9) {,,,,};
  node[shape=circle split,circle split part fill={green,violet}] (p3) at (144:1.9) {,,,,};
  node[shape=circle split,circle split part fill={green,violet}] (p4) at (216:1.9) {,,,,};
  node[shape=circle split,circle split part fill={orange,pink}] (p5) at (288:1.9) {,,,,};

  draw (p1) -- (p2);
  draw (p1) -- (p3);
  draw (p1) -- (p4);
  draw (p1) -- (p5);
  draw (p2) -- (p3);
  draw (p2) -- (p4);
  draw (p2) -- (p5);
  draw (p3) -- (p5);
end{tikzpicture}
end{document}