R postscript command (colormodel cmyk) not working?

I'm producing an EPS image in R, with black (box and axes) and red (points).

postscript('test.eps',colormodel='cmyk')
plot(1:10,col='red')
dev.off()

Using ImageMagick's identify, shouldn't it be in CMYK color model, instead of sRGB?

$ identify test.eps 
test.eps PS 576x756 576x756+0+0 16-bit sRGB 9.83KB 0.000u 0:00.000