The “Transaction history” page gives you a series of options to track your activity with Colossus, including deposits, withdrawals and P&L for any selected period. If you are accessing the site via a browser, click on your username in the top right corner, or, in the Colossus app, use the ‘hamburger’ menu on the right, then click “Transaction history“.
Note that the P&L option counts a bet as a loss on the day you place it, including contributions to Syndicate tickets that are not yet filled, and any returns from bets are counted as profit on the day such returns are applied to your account, including adjustments for voided Syndicate contributions.