In the Configuration Editor for autoexec.cfg you’ll see Server Name:
To add color around words, wrap these around the words.

<color=HERE>Words</color>

An example name, which can have multiple colors:
<color=#FF0000>Words</color> <color=#0000A0>Awesome Server</color>

What that would look like ingame:
Words Awesome Server

Some helpful colors codes:
Red #FF0000
White #FFFFFF (White #FFFFFF)
Cyan #00FFFF
Silver #C0C0C0
Blue #0000FF
Gray or Grey #808080
DarkBlue #0000A0
Black #000000
LightBlue #ADD8E6
Orange #FFA500
Purple #800080
Brown #A52A2A
Yellow #FFFF00
Maroon #800000
Lime #00FF00
Green #008000
Magenta #FF00FF
Olive #808000