HSD 32 Bit Data Bus To Serial Converter Via A Microcontroller - Data Sniffer To Read The Data Bus (32Bit)

Im working on a HSD 32 bit data bus to serial converter via a microcontroller. Now first I want to make a sort of data sniffer to read the data bus (32Bit) .All on the controller side is working and the stream of bytes are coming in via RS232 as 4 bytes in HEX like FD,A5,45,8B . I already converted the bytes in Dec and ASCII to determine what is passed true the bus and how fast and stuff.. Now that is all correct and working very well if the LSB (least significant bit) of the 32 data bus is Data line 0 and the MSB (most significant bit) is Data line 31 but if that is not the case I need to invert the 32Bits (like as I would invert the connector on the bus) . How do I best do this using the 4 bytes I send from the micro controller.

Example:

(MSB) 01001000 01100101 01101100 01110000 (LSB)
HEX= 48 65 6C 70
DEC= 72,101,108,112
ASCII= H E L P

I need to invert it with a button to:

(MSB) 00001110 00110110 10100110 00010010 (LSB)
HEX= 0E 36 A6 12
DEC= 14,54,166,18
ASCII= (SO) 6 : (DC2)