Here’s line color different to point color:
using Colors
cs = ["fn1", "0.3x+1", "0.3x+1.1"]
dpalette(n::Int) = LCHuv.(65, 100, 15:(360/n):374)
palette2 = ["deepskyblue","yellow3", "hotpink", "blue", "orange", "orchid"]
p = plot(iris,
layer(x=:SepalLength, y=:SepalWidth, color=:Species),
layer(y=fs, xmin=[4.4], xmax=[8], Stat.func, Geom.line, color=cs, order=2),
# Scale.color_discrete_manual(dpalette(6)...)
Scale.color_discrete_manual(palette2...),
Guide.colorkey(title="Iris")
)