The MAC address printed on your beacons is just a nicely formatted version in hexadecimal of the 6 byte address. What you get from Python are the actual 6 bytes themselves (hence the b' at the start) and when you print them they get turned into the correspond ASCII characters for that value (or \xYY if it's not a printable character)
You can use the binascii.hexlify function to turn each of those bytes into hexadecimal and make a string which is closer to what you have. For example your b'FS\xbd\x8c\xd2\x11'>>> import binascii >>> binascii.hexlify(b'FS\xbd\x8c\xd2\x11') b'4653bd8cd211'
So this address is 46:53:bd:8c:d2:11
Of course you can split into pairs, add the colons and make all letters uppercase too using standard string manipulation.