After generating the first block, we get the address and can generate the next one - the arrow from the first block on the left to the next block of a different size on the right.
after generating the second block, change the address in the first one, so the back arrow and the new arrow to the right for generating the third block and etc.
All the relations between blocks have one direction, being (imo) always the most important relation the "direction" of the hash which points always backwards, from a block to the previous block.
If you want to include an arrow pointing forwards (as I interpret, that the miner which generates the block makes it possible to append the next block, or as I wrote before, as a general timeline starting at the genesis block), it should be of another color or tone.
And the space between the blocks should be empty, I think. You could, in theory, try to include a symbol representing the mempool, but that would be overly complicated imo.