add the script into .zshrc, and u can change the color of tab. from http://kendsnyder.com/tab-colors-in-iterm2-v10/

tab-color-in-iterm2.zsh

# iterm coloring
function tab-color() {
    if [[ $# == 1 ]]
    then
        # convert hex to decimal
        hex=$1
        if [[ ${hex:0:1} == "#" ]]
        then
            # strip leading hash sign
            hex=${hex:1:6}
        fi
        if [[ ${#hex} == 3 ]]
        then
            # handle 3-letter hex codes
            hex="${hex:0:1}${hex:0:1}${hex:1:1}${hex:1:1}${hex:2:1}${hex:2:1}"
        fi
        r=$(printf "%d" 0x${hex:0:2})
        g=$(printf "%d" 0x${hex:2:2})
        b=$(printf "%d" 0x${hex:4:2})
    else
        r=$1
        g=$2
        b=$3
    fi
    echo -ne "\033]6;1;bg;red;brightness;$r\a"
    echo -ne "\033]6;1;bg;green;brightness;$g\a"
    echo -ne "\033]6;1;bg;blue;brightness;$b\a"
}
function tab-red() { tab-color 203 111 111; }
function tab-green() { tab-color 6cc276; }
function tab-yellow() { tab-color "#e8e9ac"; }
function tab-blue() { tab-color 6f8ccc; }
function tab-purple() { tab-color a789d4; }
function tab-orange() { tab-color fbbc79; }
function tab-white() { tab-color fff; }
function tab-gray() { tab-color c3c3c3c; }