I think an additional CTE may be what you want:

WITH cteTestGroups (iGroupSrNo, cTitle, iSubGroupSrNo, cSubGroup AS
(SELECT MIN(A.iSrNo), B.cTitle, MIN(C.iSrNo), C.cSubGroup
 FROM sReqSlipTestGroup A
 JOIN mTestGroups B ON B.iID = A.iTestGroupID
 JOIN lTestGroupsTest C ON C.iPID = B.iID
JOIN mTests D ON D.iID = C.iTestID
 WHERE A.iPID = 1
 GROUP BY B.lNewPage, A.iSrNo, B.cTitle, C.cSubGroup),
cteOrderGroups(cTitle, cOrder) AS
(select cTitle, min(iGroupSrNo)
from cteTestGroups
group by 1)
       
SELECT cteTG.*
FROM cteTestGroups cteTG
JOIN cteOrderGroups cteOG on cteTG.cTitle = cteOG.cTitle
ORDER BY cteOG.cOrder, cteTG.iSubGroupSrNo

Maybe things could be simplified further, but this at least ought to work.
Set

Thanks Set for starting me on the right track.  Please see my finalized query below which gets me to the expected result.

Kind regards
Bhavbhuti

    WITH cteTestGroups AS (
        SELECT MIN(sReqSlipTestGroup.iSrNo)  AS iGroupSrNo
                , MAX(lTestGroupsTest.iSrNo) AS iSubGroupSrNo
                , mTestGroups.cTitle
                , lTestGroupsTest.cSubGroup
            FROM sReqSlipTestGroup sReqSlipTestGroup
                JOIN mTestGroups mTestGroups
                    ON  mTestGroups.iID = sReqSlipTestGroup.iTestGroupID
                JOIN lTestGroupsTest lTestGroupsTest
                    ON lTestGroupsTest.iPID = mTestGroups.iID
                JOIN mTests mTests
                    ON mTests.iID = lTestGroupsTest.iTestID
            WHERE sReqSlipTestGroup.iPID = 1
            GROUP BY mTestGroups.lNewPage
                , mTestGroups.cTitle
                , lTestGroupsTest.cSubGroup
            ORDER BY 1, 2, 3, 4
        )

        , cteTitleOrder AS (
        SELECT MIN(cteTG.iGroupSrNo) AS iTitleOrder
                , cteTG.cTitle
            FROM cteTestGroups cteTG
            GROUP BY cteTG.cTitle
            ORDER BY 1
        )

        , cteFinalOrder AS (
        SELECT cteTitleOrder.iTitleOrder
                , cteTestGroups.iGroupSrNo
                , cteTestGroups.iSubGroupSrNo
                , cteTestGroups.cTitle
                , cteTestGroups.cSubGroup
            FROM cteTestGroups
                JOIN cteTitleOrder
                    ON cteTitleOrder.cTitle = cteTestGroups.cTitle
            ORDER BY cteTitleOrder.iTitleOrder
        )


        SELECT sReqSlipTestGroup.*
                , mTestGroups.*
                , lTestGroupsTest.*
                , mTests.*
            FROM sReqSlipTestGroup sReqSlipTestGroup
                JOIN mTestGroups mTestGroups
                    ON  mTestGroups.iID = sReqSlipTestGroup.iTestGroupID
                JOIN lTestGroupsTest lTestGroupsTest
                    ON lTestGroupsTest.iPID = mTestGroups.iID
                LEFT JOIN cteFinalOrder
                    ON cteFinalOrder.cTitle = mTestGroups.cTitle
                    AND cteFinalOrder.cSubGroup = lTestGroupsTest.cSubGroup
                JOIN mTests mTests
                    ON mTests.iID = lTestGroupsTest.iTestID
            WHERE sReqSlipTestGroup.iPID = 1
            ORDER BY cteFinalOrder.iTitleOrder
                , cteFinalOrder.iGroupSrNo
                , cteFinalOrder.iSubGroupSrNo
                , sReqSlipTestGroup.iSrNo
                , lTestGroupsTest.iSrNo