It looks like your "series" option is listed outside the ChartWrapper's "options" parameter, so if that's where you are trying to set the colors, it definitely won't work. Try this instead:
ComboChart = new google.visualization.ChartWrapper({
chartType: "ComboChart",
containerId: "combochart",
options: {
chartArea: {
height: "80%",
width: "70%",
},
seriesType: "bars",
isStacked:"True",
series: {
0: { // set the options for the first series (columns)
type: "bars",
targetAxisIndex: 0,
color: 'red'
},
1: { // set the options for the second series (line)
type: "line",
targetAxisIndex: 1,
color: 'maroon'
},
2: { // set the options for the second series (line)
type: "line",
targetAxisIndex: 2,
color: '#338067'
},
3: { // set the options for the second series (line)
type: "line",
targetAxisIndex: 3,
color: '#FC53D2'
}
}
}
});